未收到 WifiManager.NETWORK_STATE_CHANGED_ACTION答案

【问题标题】：WifiManager.NETWORK_STATE_CHANGED_ACTION not received未收到 WifiManager.NETWORK_STATE_CHANGED_ACTION
【发布时间】：2018-12-19 11:24:37
【问题描述】：

我想知道设备何时连接到 Wi-Fi 网络。问题是我没有收到来自 WifiManager.NETWORK_STATE_CHANGED_ACTION

的任何 Intent

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    IntentFilter intentFilter = new IntentFilter();
    intentFilter.addAction(WifiManager.NETWORK_STATE_CHANGED_ACTION);

    LocalBroadcastManager.getInstance(this).registerReceiver(MainActivity.wifiBroadcastReceiver = new BroadcastReceiver() {
        public void onReceive(Context context, Intent intent) {
            Log.i("LOG", "onReceive"); // This is never executed
        }
    }, intentFilter);
}

权限

<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.CHANGE_NETWORK_STATE" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />

WifiManager.NETWORK_STATE_CHANGED_ACTION 是否需要其他一些权限？

【问题讨论】：

标签： android android-intent permissions wifi state

【解决方案1】：

这里LocalBroadcastManager 不起作用。 LocalBroadcastManager 只会监听通过 LocalBroadcastManager 发送的意图。但是NETWORK_STATE_CHANGED_ACTION会被系统广播，所以需要注册动态BroadcastReceiver来监听NETWORK_STATE_CHANGED_ACTION。

例如..

在你的 Activity 中定义一个 BroadcastReceiver 为

private BroadcastReceiver receiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            NetworkInfo info = intent.getParcelableExtra(WifiManager.EXTRA_NETWORK_INFO);
            Log.i("Wi-Fi network state", info.getDetailedState().toString());
        }
    };

并注册和注销它为

@Override
    protected void onCreate(Bundle savedInstanceState) {
        ......

        IntentFilter intentFilter = new IntentFilter();
        intentFilter.addAction(WifiManager.NETWORK_STATE_CHANGED_ACTION);
        registerReceiver(receiver, intentFilter);
    }

    @Override
    protected void onDestroy() {
        unregisterReceiver(receiver);
        super.onDestroy();
    }

【讨论】：